That's the advice of Karl Denninger when confronted by an attacker such as the terrorist at the Orlando night club on Saturday evening. It ties in with what I had to say on the subject.
The reason for this is simple: If you are already dead then any act you undertake can only improve the outcome. It cannot make it worse, because the worst possible outcome has already happened.
You must accept and internalize the fact that the cops will not save you; they will, however, dutifully inventory your dead body 12 hours later.
. . .
We used to, as Americans, face this reality on a regular basis. We had a large percentage of our population that were drafted and sent to war from time to time and faced bullets whizzing by their heads for months or years, with many of their friends falling to the ones that found their mark. We had a frontier where you faced snakes, Indians (interested in your scalp as you were, from their point of view, invading their land!) and simple starvation or running out of water, and more than a few succumbed to one of the above. Disease felled even more, regularly. There was no such thing as a "safe space" nor the idiot "progressives" demanding and putting forward same as "rights"; that is utter crap yet it has massively contributed to the "oh my God hide in the bathroom!" mentality.
Simply put you must individually perform this exercise, starting right now. You must be prepared on a mental basis to adopt the "I'm dead" belief and position in mind, body and soul if confronted with such a situation.
. . .
Because ... when that jackass shows up if he doesn't spend one of his first magazine's rounds on you there will be a short period of time, just a few seconds, where you have the ability to disrupt his attack and you must seize that moment and attempt to do exactly that.
There's much more at the link. Go read, and ponder. He's right.